Spitzer Leads NASA's Great Observatories to Uncover Black Holes, Other Hidden Objects in the Distant Universe

June 1, 2004: Astronomers unveiled the deepest images from NASA's new Spitzer Space
Telescope today, and announced the detection of distant objects —
including several supermassive black holes — that are nearly invisible in
even the deepest images from telescopes operating at other wavelengths.

Q & A: Understanding the Discovery

1.
How is a supermassive black hole different from normal black holes?

Supermassive black holes formed early in the universe and accompanied
galaxy formation. Hubble research finds that they are common among
galaxies. They are millions or billions of times more massive than
black holes that are left behind after a star explodes.

2.
What's the difference between a supermassive black hole and an AGN?

AGNs  active galactic nuclei  are supermassive black holes that are
accreting gas. The black hole heats the gas to millions of degrees, where
it glows in X-rays. This makes the region around the black hole glow
brightly across the universe.

3.
Why are the AGNs so far away?

Black holes were well-fed in the early universe. There was a lot of gas
from them to accrete from galaxy collisions, which were more frequent
when the expanding universe was smaller, so very distant galaxies are
more likely to have AGNs.

4.
How can a black hole be hidden from view in visible-light images?

Black holes can be hidden behind dusty, donut-shaped features, which are
common in AGNs. Or, they can be so far away that all their light is
stretched into the infrared region of the spectrum.